Care receivers get bedsores easily if they need to be in bed for a long time, which is severely painful for them. Bedsores occur especially in parts of a body such as a waist, shoulders, and ankles which protrude with bones when blood circulation becomes poor there by pressure of the body weight, resulting in necrosis.
Posture of a care receiver need to be changed appropriately in order to prevent bedsores, and in particular when the care receiver has difficulty moving his/her body by himself/herself, appropriate countermeasures such as putting a pillow under the waist of the care receiver need to be taken by a caregiver.
The caregiver needs to work for preventing bedsores by moving a heavy body of the care receiver, which is a hard labor. Moreover, the work needs to be done night and day, for example every one or two hours, which is a heavy burden for the caregiver. Also, the care receiver tends to feel a mental burden about forcing a hard labor on the caregiver.
In order to reduce such a burden on the caregiver (and the care receiver), a technique of making a portion of a bed upper surface (sleeping surface) of a nursing bed movable so as to change posture of the care receiver by appropriately moving the movable portion of the bed upper surface manually or using power (refer to Patent Documents 1 to 7 below).